view tests/test-merge-remove.t @ 26243:836291420d53

revlog: optionally cache the full text when adding revisions

revlog instances can cache the full text of a single revision. Typically
the most recently read revision is cached.

When adding a delta group via addgroup() and _addrevision(), the
full text isn't always computed: sometimes only the passed in delta is
sufficient for adding a new revision to the revlog.

When writing the changelog from a delta group, the just-added full
text revision is always read immediately after it is written because
the changegroup code needs to extract the set of files from the entry.
In other words, revision() is *always* being called and caching the full
text of the just-added revision is guaranteed to result in a cache hit,
making the cache worthwhile.

This patch adds support to _addrevision() for always building and
caching the full text. This option is currently only active when
processing changelog entries from a changegroup.

While the total number of revision() calls is the same, the location
matters: buildtext() calls into revision() on the base revision when
building the full text of the just-added revision. Since the previous
revision's _addrevision() built the full text and the the previous
revision is likely the base revision, this means that the base
revision's full text is likely cached and can be used to compute the
current full text from just a delta. No extra I/O required.

The end result is the changelog isn't opened and read after adding every
revision from a changegroup.

On my 2013 MacBook Pro running OS X 10.10.5 from an SSD and Python 2.7,
this patch impacted the time taken to apply ~262,000 changesets from a
mozilla-central gzip bundle:

  before: ~43s
  after:  ~32s

~25% reduction in changelog processing times. Not bad.

  $ hg init

  $ echo foo > foo
  $ echo bar > bar
  $ hg ci -qAm 'add foo bar'

  $ echo foo2 >> foo
  $ echo bleh > bar
  $ hg ci -m 'change foo bar'

  $ hg up -qC 0
  $ hg mv foo foo1
  $ echo foo1 > foo1
  $ hg cat foo >> foo1
  $ hg ci -m 'mv foo foo1'
  created new head

  $ hg merge
  merging foo1 and foo to foo1
  1 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)

  $ hg debugstate --nodates
  m   0         -2 unset               bar
  m   0         -2 unset               foo1
  copy: foo -> foo1

  $ hg st -q
  M bar
  M foo1


Removing foo1 and bar:

  $ cp foo1 F
  $ cp bar B
  $ hg rm -f foo1 bar

  $ hg debugstate --nodates
  r   0         -1 set                 bar
  r   0         -1 set                 foo1
  copy: foo -> foo1

  $ hg st -qC
  R bar
  R foo1


Re-adding foo1 and bar:

  $ cp F foo1
  $ cp B bar
  $ hg add -v foo1 bar
  adding bar
  adding foo1

  $ hg debugstate --nodates
  n   0         -2 unset               bar
  n   0         -2 unset               foo1
  copy: foo -> foo1

  $ hg st -qC
  M bar
  M foo1
    foo


Reverting foo1 and bar:

  $ hg revert -vr . foo1 bar
  saving current version of bar as bar.orig
  reverting bar
  saving current version of foo1 as foo1.orig
  reverting foo1

  $ hg debugstate --nodates
  n   0         -2 unset               bar
  n   0         -2 unset               foo1
  copy: foo -> foo1

  $ hg st -qC
  M bar
  M foo1
    foo

  $ hg diff

Merge should not overwrite local file that is untracked after remove

  $ rm *
  $ hg up -qC
  $ hg rm bar
  $ hg ci -m 'remove bar'
  $ echo 'memories of buried pirate treasure' > bar
  $ hg merge
  bar: untracked file differs
  abort: untracked files in working directory differ from files in requested revision
  [255]
  $ cat bar
  memories of buried pirate treasure

Those who use force will lose

  $ hg merge -f
  remote changed bar which local deleted
  use (c)hanged version or leave (d)eleted? c
  merging foo1 and foo to foo1
  1 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ cat bar
  bleh
  $ hg st
  M bar
  M foo1